process simulator development at iter...r. maekawa ped/csed/cse page 19/63 modeling cicc (cstr;...

/63R. MAEKAWA PED/CSED/CSE

Process simulator development at ITER

Ryuji MAEKAWA

ITER Organization

Oct. 1, 2019 at EASISchool

CEA


Plant Simulator for TOKAMAK (Magnet & Cryoplant)

• Reproducing virtual plant operation in a real time (in WS/PC)

– To understand the highly complex plant process

– Versatile tool to verify control strategy

– Focus on the most demanding operation & fast events (PD, FD of magnet)


Development Program

• ITER cryo-system simulator concept (back in 2011)

– CERN (Refrigerator)-25 kW refrigerator model (2011-2013, 2016)

– NIFS-development of Superconducting Magnet model w/ ACBs (2011-ongoing)

– Coupling two models for Cryogenic system simulator (2017-2018)


• Achieve Q > 10 ~500MW thermal energy– Current record Q~0.67 by JET

• Schedule– 2025 –First Plasma

– 2035-DT operation

• Plasma- 150 million C

• Superconducting magnet -269 C


CRYOGENICS-SUSTAIN OPERATION of TOKAMAK

• COLD-MASS• Approximately 10,000 tons• A forced-flow cooling w/ SHe

• Superconducting magnet system w/ dedicated ACB• Thermo-hydraulic length

• TF-380 m• CS-152 m• PF-199-454 m• CC-130, 160, 200 m• TF structure ~20 m


Challenge for Cryogenics?

• Substantial dynamic heat load (>30 MJ)

– Initial Magnetization by CS

– Position control of plasma (PF/CS)• Eddy current generation and AC losses

– Nuclear heat load; under assessment • 14.6 kW now it goes up to > 20 kW…

Based on the Vincenta® simulationNumerical code to look into the conductor stability


Why plant simulator?

• 1st time for Cryoplant to handle 35-100kW variation in 30 min

• 3 refrigerators connected in parallel to produce 100kW (max)

• Severe operation for CS (IM)

– Cross check operation of cold-circulator/compressor

• Thermal energy mitigation in the case of plasma disruption


OBJECTIVE-Plant simulator development

• To understand complex Cryogenic system for Tokamak (CRYOPLANT & MAGNET)

– FULL SCOPE PLANT MODEL (INTERACTIVE) w/ SC magnet system

Decision assistance for operation

Optimization

Controllability assessment

Operator Training

Plant diagnosis

Fault Detection/Recovery


Outline

• Process simulator

• MODELING & RESULT

– Magnet (CS, TF, PF/CC, TF structure) (Visual Modeler®)

• SUMMARY


SIMULATION MODEL…

Fidelity?


How “Valid” are Simulation Model?• Target system

• Simulation Model

Complete Overlap Partial Overlap No Overlap..


Modeling and Validation/Benchmark

• Comparison of process simulation data w/ REAL SYSTEM

– Agreement/Discrepancy

– FEEDBACK Model revision

Modeling & Simulation REQUIREMENT

Acceptance CRITERIA

TRADE OFF Accuracy vs Speed


Scope of development

TF

2.2kg/s

PF/CC

2.4 kg/sCP

E-7

CS

2.0kg/s

E-3

ST

2.7kg/s

E-1

ST-23 kW

Cold Compressor

SHe LHe heat exchanger

Cold Circulator

Clients

CB1 CB2 CB3

Cryoplant 25kW x3 CBs

TF-12 kW

PF/CC-7 kW

CP-5 kW

CTCB

CS-17 kW

LHe Tank

LHe Subcooler

WCS1 WCS2 WCS3

Buffer Tank

Nominal operation - 75 kW

The maximum power - 100 kW (utilization of LHe tank)

Design value for HX

Ryuji MAEKAWA Dec.6, 2013/

revised Jan. 13, 2016 (reducing the

max power from 110 to 100 kW

Cryoplant Termination Cold Box

P-5

• Distributed cooling for 5 sub-system

• ACB consists of;

• Subcooler (saturated/subcooled)

• SHE pump for circulation of

coolant

• Cold compressor/circulator

• Control valves + process piping


MAGNET MODELING

…


Critical Issue for dynamic simulator

• How to model Cable-in-Conduit-Conductor (CICC)?

• N-S eqn?


Dynamic heat load on CS conductor

• 8 MJ in 1800 s - 50% deposition within 70 s


Tout

t

Tout

P

From CHATS 2011 presentation by B. RousetteCEA-Grenoble


FORCED FLOW SHe COOLING

• Modeling of a forced-flow Supercritical Helium Cooling

– Required for Magnet as well as structure cooling loop

– Utilize 1st law of thermo-dynamics to describe energy balance in the loop

dt

dEWQ

dAnvP

edVet

WQ

SCVC


MODELING CICC (CSTR; Continuous Stirred Tank Reactor)

• Capture thermo-hydraulic behavior of forced flow SHe

– Faster convergence with high accuracy

– ST cooling (20m long), S/C cooling (>100m long)

– CSTR MODELING to re-produce thermo-hydraulic behavior• QUANTIFY the rate of reaction in the given element

• IMPULSE response (Continuous Stirred Tank Reactor/Plug Flow Reactor)

CSTR PFR

to tr to trto

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R. MAEKAWA PED/CSED/CSE

Description of residence time and reaction

tm; averaged residence time• Residence Time Distribution

𝐸 𝜃 =𝑁

𝑁 − 1 !𝑁𝜃 𝑁−1𝑒𝑥𝑝 −𝑁𝜃


Validation of module by CSMC test (NAKA-JARIE)

• CICC model based on # of CSTR unit connecting in series

• Temperature profile of CSMC test results compared w/ simulation

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CS SIMULATION

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Objective of CS process simulation

• Assess the impact on IM

– Cold circulator operation

• Operation stability

– Cross check functionality of ACB in terms of process control

– Supply 4.3 K SHe to CS modules

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• CICC based on CSTR model

– Spatial discretization 70 along the conductor length

– Total of 480 discretization to capture thermo-hydraulic characteristics in CICC (CS)

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Process control ACB

ASC: Anti-Surge Controller ASV: Anti-Surge Valve IV_S: Isolation Valve Supply IV_R: Isolation Valve Return

PT: Pressure Transmitter LC: Level Controller PC: Pressure Controller HX: Heat Exchanger MC: Mitigation Control FT: Flow Transmitter

Cold circulator

ASV (CS bypass)

IV_SIV_R

LHe Subcooler

HXs

PT

ASC

PC

LC

Cold BoxSHe Supply

CS ModuleCS Module

Cold Comp.

PT

ASC

MC

ASV

ASC

FT

TF

2.2kg/s

PF/CC

2.4 kg/sCP

E-7

CS

2.0kg/s

E-3

ST

2.7kg/s

E-1

ST-23 kW

Cold Compressor

SHe LHe heat exchanger

Cold Circulator

Clients

CB1 CB2 CB3

Cryoplant 25kW x3 CBs

TF-12 kW

PF/CC-7 kW

CP-5 kW

CTCB

CS-17 kW

LHe Tank

LHe Subcooler

WCS1 WCS2 WCS3

Buffer Tank

Nominal operation - 75 kW

The maximum power - 100 kW (utilization of LHe tank)

Design value for HX

Ryuji MAEKAWA Dec.6, 2013/

revised Jan. 13, 2016 (reducing the

max power from 110 to 100 kW

Cryoplant Termination Cold Box

P-5

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CS cooling loop

• Pressure (loop) and Temperature (at HX) variations

300

400

500

600

700

800

900

0 900 1800 2700 3600 4500 5400 6300 7200

Pre

ssu

re (

kP

a)

Time (s)

4.0

4.5

5.0

5.5

6.0

6.5

0 900 1800 2700 3600 4500 5400 6300 7200

Tem

per

atu

re(K

)

Time(s)

Inlet

Outlet

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Modeling of Cold circulator/compressor

Characteristic Curve for circulator/comp.normalized

0.34

0.36

0.38

0.40

0.42

0.44

0.46

0 0.005 0.01 0.015 0.02 0.025 0.03P

ress

ure

coef

fici

ent

(-)

Flow coefficient (-)

simulation

characteristic curve

Surge

Risk

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Process control -ASV

• Impose operation boundary to avoid surge

– ASV• Active/passive

– Simply open ASV at the onset of IM

– Circulator dP regulation

Cold circulator

ASV (CS bypass)

IV_SIV_R

LHe Subcooler

HXs

PT

ASC

PC

LC

Cold BoxSHe Supply

CS ModuleCS Module

Cold Comp.

PT

ASC

MC

ASV

ASC

FT

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Impact on SHe pump operation at IM

• Risk to go into surge at the IM due to drastic P increase

– Driving operation point in a short time, a few seconds

0.34

0.36

0.38

0.40

0.42

0.44

0.46

0 0.005 0.01 0.015 0.02 0.025 0.03

Pre

ssu

re c

oef

fici

ent

(-)


simulation


Surge

Risk

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0 1800 3600 5400 7200

Flo

w c

oef

fici

ent

(-)

Time (s)

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Result of ASV

• Effective regulation via ASV to limit the operation range of SHe pump

0.34

0.36

0.38

0.40

0.42

0.44

0.46

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035

Pre

ssu

re c

oef

fice

nt(

-)

Flow coefficient(-)

Characteristic curve

simulation

0.34

0.36

0.38

0.40

0.42

0.44

0.46

0 0.005 0.01 0.015 0.02 0.025 0.03

Pre

ssu

re c

oef

fici

ent

(-)


simulation


Surge

Risk


CS simulation brings…

• Identify the risk of operation

• Implement control logic

– Simulation demonstrated successful mitigation of risk

– Validation is required with the real system

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Rule of thumb!

• Model has to be validated before use!

• Simulation model represents the physical model based on the equations

• ITERATION/REVISION !!

– SIMULATION ≠ REALITY

– Engineering verification

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Summary-Current status

• Running global simulation under fast event

– Plasma disruption followed by the fast energy discharge

• Complete the development for

– He cryoplant (EcosimPro®)• 3 helium refrigerator operated in parallel

– ACB (5 distribution boxes) (EcosimPro® & Visual Modeler®)

– Superconducting magnet system (Visual Modeler®)• TF

• TF structure (TF coil case + support)

• CS

• PF/CC

• Benchmark against SUPERMAGNET®

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process simulator development at iter...r. maekawa ped/csed/cse page 19/63 modeling cicc (cstr;...

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